Convert Micrometers to Thou
1 micrometer is 0.04 thou. One micrometer is exactly 0.0393700787402 thou.
One micrometer is 0.039370079 thou. To convert micrometers to thou, multiply by 0.039370079; to go the other way, divide by 0.039370079 or multiply by 25.4. The relation is exact but the figure is not: it is a rounding of a number that does not terminate, and it follows from NIST. A millionth of a meter, still widely called a micron.
Factor checked against the defining standard · How we check
- Micrometers × 0.039370079
1 * 0.03937010.039 thou
1 micrometer in every length unit
| Unit | Value | Exact factor |
|---|---|---|
| inches | 0.00003937007874 in | × 0.0000393700787402 |
| feet | 0.000003280839895 ft | × 0.00000328083989501 |
| yards | 0.000001093613298 yd | × 0.00000109361329834 |
| miles | 0.0000000006213711922 mi | × 0.000000000621371192237 |
| millimeters | 0.001 mm | × 0.001 |
| decimetres | 0.00001 dm | × 0.00001 |
| centimeters | 0.0001 cm | × 0.0001 |
| meters | 0.000001 m | × 0.000001 |
| kilometers | 0.000000001 km | × 0.000000001 |
| nautical miles | 0.0000000005399568035 nmi | × 0.000000000539956803456 |
| micrometers (as entered) | 1 µm | — |
| nanometers | 1,000 nm | × 1,000 |
| thou | 0.03937007874 thou | × 0.0393700787402 |
Factors are entered by hand from NIST rather than derived from a units library, so the ones that terminate are exact rather than rounded.
The same converter answers this pair however it is written: micrometres to thou is the British spelling of the same units — the metre and the litre are spelled that way outside the United States and the quantity does not change.
How do you convert micrometers to thou? The converter and the working
- 1.Take the measurement in micrometers.
- 2.Multiply by 0.039370079 — that is how many thou fit in one micrometer.
- 3.To go back the other way, divide by 0.039370079, or multiply by 25.4.
Worked example: 25 micrometers to thou
- Formula
- µm × 0.039370079 = thou
- Arithmetic
- 25 × 0.039370079 = 0.98 thou
- Answer
- 25 µm = 0.98 thou
The factor is rounded for display; the figure above is computed from the full value.
Micrometers to thou conversion table
| Micrometers | Thou |
|---|---|
| 1 µm | 0.04 thou |
| 2 µm | 0.08 thou |
| 3 µm | 0.12 thou |
| 4 µm | 0.16 thou |
| 5 µm | 0.2 thou |
| 6 µm | 0.24 thou |
| 7 µm | 0.28 thou |
| 8 µm | 0.31 thou |
| 9 µm | 0.35 thou |
| 10 µm | 0.39 thou |
| 12 µm | 0.47 thou |
| 15 µm | 0.59 thou |
| 20 µm | 0.79 thou |
| 25 µm | 0.98 thou |
| 50 µm | 1.97 thou |
| 100 µm | 3.94 thou |
| 200 µm | 7.87 thou |
| 300 µm | 11.81 thou |
| 500 µm | 19.69 thou |
| 1000 µm | 39.37 thou |
| 2000 µm | 78.74 thou |
| 5000 µm | 196.85 thou |
| 10000 µm | 393.7 thou |
What is a micrometer?
A millionth of a meter, still widely called a micron. Machining tolerances, filter ratings and cell diameters are all quoted here.
What is a thou?
A thousandth of an inch, exactly 25.4 micrometers, and called a mil in American workshops — the same word the metric world uses for a millimeter, which is why a drawing marked "5 mil" is worth checking twice.
How many thou are in a micrometer?
One micrometer is 0.039370079 thou. Going the other way, one thou is 25.4 micrometers. Both figures come from the same defined relation rather than from a measurement, which is why they are the same today as they were in 1959.
Every length unit here
The whole group — 13 units with their symbols and the size of each one in meters — is on the conversion index, along with every pair it makes. The table above already gives each of them relative to a micrometer.
Source: NIST — international yard and pound agreement (inch = 25.4 mm exactly)
Cite this page
- APA
- Rule Calculator. (2026). Convert Micrometers to thou. Rule Calculator. https://rulecalculators.com/convert/micrometer-to-thou
- MLA
- "Convert Micrometers to thou." Rule Calculator, August 16, 2026, https://rulecalculators.com/convert/micrometer-to-thou.
- Chicago
- Rule Calculator. "Convert Micrometers to thou." Rule Calculator. Last reviewed August 16, 2026. https://rulecalculators.com/convert/micrometer-to-thou.
The date is when the figures on this page were last checked against their source, not the day you opened it. Add your own access date if your style needs one.
Questions people actually ask
- How many thou are in a micrometer?
- 0.039370079. A thousandth of an inch, exactly 25.4 micrometers, and called a mil in American workshops — the same word the metric world uses for a millimeter, which is why a drawing marked "5 mil" is worth checking twice.
- How do I convert thou back to micrometers?
- Divide by 0.039370079, or multiply by 25.4 — they are the same operation.
Other length conversions
Thou to micrometers — the same conversion the other way.